The invention relates to a sensor arrangement and to a method for determining a rotational angle.
In the field of torque sensors and rotational angle sensors, nowadays magnetic measuring principles are frequently used. In such torque sensors, a magnetic field which changes during a rotational movement is usually detected with Hall sensors, and an identified signal is converted into a rotational angle signal or torque signal.
According to the prior art, in order to implement a torque sensor, a magnet unit (MU) and a carrier of magnetic-flux-conducting rings (FTU=“Flux Tube Unit”) are mounted on two shafts which are connected to one another by means of a torsion bar. A sensor unit (SU) is attached to a surrounding housing by means of a plug or a circumferential plug-type connection. Here, it is not necessary to integrate an unambiguous steering angle measurement without a rotation counter.
Documents EP 2 078 930 A1 and EP 2 080 991 A1 each disclose rotational angle sensors with which it is possible to determine a rotation of a shaft relative to a stator. Here, the rotational angle sensor is a large gearwheel which surrounds the shaft and which interacts with a small gearwheel which is attached to the stator, with the result that when the shaft rotates the small gearwheel which is attached to the stator is also made to rotate. The rotational angle of the shaft can be determined in a first way from the rotation of the small gearwheel which is attached to the stator. Furthermore, a magnet is attached to the shaft, and when the shaft rotates said magnet also rotates. The magnetic field of this magnet which changes as a result of the rotation is sensed by magnetic sensors, with the result that the rotational angle of the shaft can therefore be sensed in a second way. In both specified documents there is also provision that the magnet which is attached to the shaft can be circular. Alternatively, it is also possible for a circumference of this magnet to be of elliptical design.